SALT LAKE CITY — Major changes to the missionary program of The Church of Jesus Christ of Latter-day Saints, the announcement of new temples in Arizona and Peru and stirring sermons from church leaders highlighted the first day of the church's 182nd Semiannual General Conference Saturday.

After welcoming a near-capacity crowd to the LDS Church's 21,000-seat Conference Center on a bright, clear, crisp fall morning, church President Thomas S. Monson announced that effective immediately, young men may begin their full-time missionary service following their graduation from high school, even if they are only 18 at the time. And young women, who have not been eligible for full-time missionary service until age 21, may now begin their service at age 19.

"I am not suggesting that all young men will — or should — serve at this earlier age," President Monson said. Rather, he said, the option is now available based on individual circumstances and the recommendation of their local church leaders.

"We reaffirm that missionary work is a priesthood duty," President Monson said. "Young women are not under the same mandate to serve." But, he added, the young women missionaries "make a valuable contribution as missionaries, and we welcome their service."

Young men and women seated in the Conference Center reacted immediately to the announcement. Dropped jaws reflected amazement and surprise, and huge smiles and excited whispers indicated a sudden burst of excitement.

Elder Quentin L. Cook of the Quorum of the Twelve Apostles, who followed President Monson to the Conference Center pulpit Saturday morning, began his sermon with an observation that the new age requirements will "make a difference" for LDS missions and missionaries. He recalled that he was serving as a full-time missionary in Great Britain at the time the age for missionary service for young men was lowered to 19, adding that the first 19-year-old missionary in his mission was Elder Jeffrey R. Holland, who later served as his missionary companion and is now one of his colleagues in the Quorum of the Twelve Apostles.

"That was an incredible addition to our mission," he said, smiling, adding that he believes this newly announced change in age requirements will be similarly beneficial to LDS missionary work.

Later in the session, Elder Russell M. Nelson of the Quorum of the Twelve Apostles also mentioned the policy change, noting, "We are thrilled with the announcement."

"Through this option more of our youth may enjoy the blessings of a mission," Elder Nelson said at the start of a sermon that was addressed to non-Latter-day Saints, urging them to seek out the LDS missionaries. "The decision to serve a mission will shape the spiritual destiny of the missionary, his or her spouse, and their posterity for generations to come."

A press conference was held in between general conference sessions, during which Elder Nelson and Elder Holland elaborated on the change.

Almost lost in the excitement of the missionary age change was President Monson's earlier announcement of two new LDS temples, one in Tucson, Ariz., and one in Arequipa, Peru. The Tucson Arizona Temple will be Arizona's sixth temple, while the Arequipa Peru Temple will be the third in that South American country.

The two new temples bring the total number of LDS temples in operation, under construction or in the planning stages around the world to 168.

Additional church business was conducted during the Saturday afternoon session of conference when Elder Craig C. Christensen was sustained as a new member of the Presidency of the Seventy, replacing Elder Jay E. Jensen, who, along with Elders Keith K. Hilbig, Marlin K. Jensen and Octaviano Tenorio, was given general authority emeritus status.

Elder Marlin K. Jensen was also released as LDS Church historian and recorder, and Elder Steven E. Snow was sustained to those positions in his place.

At the same time, Elders Keith R. Edwards and Larry W. Gibbons were released as members of the Second Quorum of the Seventy.

President Dieter F. Uchtdorf, second counselor in the church's presiding First Presidency, counseled his listeners during the Saturday morning conference session that adherence to gospel principles and values can "help us to avoid future regrets."

"Let us resolve to cherish those we love by being by their sides, spending meaningful time with them, and cultivating treasured memories," he said. "Let us resolve to follow the Savior and work with diligence to become the person we were designed to become. Let us listen to and obey the promptings of the Holy Spirit.

"The more we devote ourselves to the pursuit of holiness and happiness, the less likely we will be on a path to regrets," President Uchtdorf continued. "The more we rely on the Savior's grace, the more we will feel during life's journey that we are on the track our Father in heaven has intended for us."

Other speakers during the session included Elder Craig C. Christensen of the Presidency of the Seventy, Elder Shayne M. Bowen of the First Quorum of the Seventy and Sister Ann M. Dibb, second counselor in the Young Women General Presidency.

Music for the morning session was provided by the Mormon Tabernacle Choir.

The Saturday afternoon conference session featured talks by four members of the Quorum of the Twelve Apostles. Elder L. Tom Perry began his talk by noting he recently celebrated his 90th birthday, making him the only person in the First Presidency or Quorum of the Twelve, as currently constituted, to have reached that milestone. In his address he discussed the responsibility of parents in the upbringing of their children.

"It is wonderful to see husbands and wives who have worked out real partnerships where they blend together their influence and communicate effectively both about their children and to their children," he said. "The onslaught of wickedness against our children is more subtle and brazen than it has ever been. Building a stronger family culture adds another layer of protection for our children, insulating them from worldly influences."

Elder Dallin H. Oaks expressed concern about social policies and practices that can harm children. He spoke openly about a wide range of behaviors that harm or disadvantage children: abortion; child abuse and neglect; unnecessary divorces spurred by so-called "no fault" divorce laws; bearing children out of wedlock; and same-sex couples choosing to raise children.

"There are surely cases when a divorce is necessary for the good of the children, but those circumstances are exceptional," he said. "In most marital contests the contending parents should give much greater weight to the interests of the children.

"Children need the emotional and personal strength that comes from being raised by two parents who are united in their marriage and their goals," he continued. "As one who was raised by a widowed mother, I know firsthand that this cannot always be achieved, but it is the ideal to be sought whenever possible."

Elder Oaks acknowledged that "some may reject" his words of counsel, "but none should resist the plea that we unite to increase our concern for the welfare and future of our children — the rising generation."

Elder M. Russell Ballard drew parallels between an industrious beehive — which requires more than 20,000 honeybees to travel the equivalent of two times around the world in order to produce a single pound of honey — and the church-at-large. He challenged Latter-day Saints to focus on giving meaningful Christian service every day.

"There is one simple daily practice that can make a difference for every member of the church," Elder Ballard said. "In your morning prayer each new day, ask Heavenly Father to guide you to recognize an opportunity to serve one of his precious children. Then go throughout the day with your heart full of faith and love, looking for someone to help. Stay focused on this, just like the honeybees focus on the flowers from which to gather nectar and pollen. ... Over time this (will) have a transformative effect upon all of our Heavenly Father's children through the extension of his love to them through us."

And Elder Neil L. Andersen provided a road map for leveraging pre-existing faith to overcome tough times. "You immerse yourself in the very things that helped build your core of faith," Elder Andersen said. "You exercise faith in Christ, you pray, you ponder the scriptures, you repent, you keep the commandments, and you serve others. ... Like the intense fire that transforms iron into steel, as we remain faithful during the fiery trial of our faith, we are spiritually refined and strengthened."

Other speakers during the afternoon session included Elders Larry Echo Hawk, Robert C. Gray and Scott D. Whiting, all members of the First Quorum of the Seventy.

Music for the session was provided by a choir of teenagers from Bennion and Taylorsville.